Base fuze protector



May 2, 1961 R. o. ROBINSON, JR 2,982,212

BASE FUZE PROTECTOR Filed Dec. 29, 1955 FIG. I.

FIG. 2.

RALPH 0. ROBINSON JR.

IIJVENTOR ATTO EYS United States Patent BASE FUZE PROTECTOR Ralph 0. Robinson, Jr., Silver Spring, Md., assignor to the United States of America as represented by the Secretary of the Navy Filed Dec. 29, 1955, Ser. No. 556,369

3 Claims. (Cl. 102-70) This invention relates generally to fuzes for cannonfired projectiles. More particularly it relates to an improved protector for base fuzes of the proximity type.

Projectile base fnzes are exposed to excessive heat, pressure and corrosive action of gases and debris produced in the gun barrel when the projectiles are fired. Proximity fuzes in aparticular are delicate devices, and it is important that they should be protected from the destructive action of such gases and debris.

Accordingly, the principal object of the present invention is to provide a cover for base fuzes to protect them from damage when projectiles on which they are mounted are fired from a gun.

A further object of the invention resides in the provision of a protector which will, after it has served its purpose, fall away from the projectile and fuze, to permit proper operation of the fuze.

A further object of the invention is to provide a protector which, when used with a radio proximity fuze, will electrically shield said fuze until the projectile mounting it has been propelled a safe distance from the gun, to the end that premature fuze action, as by stray electric charges, will be prevented.

And still another object of the invention is to provide a fuze protector which will be characterized by its extreme simplicity.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

Fig. 1 is a side elevation of a shell having a base fuze with a protector, according to one modification of the invention, applied thereto, said protector being partially broken away and shown in section; and

Fig. 2 is an enlarged sectional view of a modified embodiment of the invention as it would appear in operative position on a projectile, only a portion of the projectile being shown.

Briefly, the invention in its simplest form consists merely of a metal billet mounted on the base of a projectile and having a recess to receive freely that portion of the fuze which projects beyond said base, a suitable adhesive being employed for temporarily holding the billet in place. In a modified form the invention comprises a pressed sheet metal member having a conical central element defining a cavity to loosely receive the fuze, a means for displaceably securing the member to the apex of the conical central element and a spring for urging the member away from the base of the projectile when the securing means has been rendered inoperative.

Referring first to Fig. 1 of the drawing, 1 represents a projectile or shell, said shell having the customary copper band 2 thereon for sealing it gas-tight in the gun barrel during firing and for engaging the rifting lands in said barrel to receive spin therefrom. All this is conventional and forms no part of the present invention, hence is not disclosed in minute detail nor discussed further.

2,982,212 Patented May 2, 1961 At the base end 3 of the projectile 1 there is shown a part of the conical tip 4 of a base fuze which projects rearwardly beyond said end 3. Preferable and most simply the rear or base surface of the projectile is plane, although this is not essential.

The protector 5 consist of a short cylindrical block of metal of sufficient strength to resist appreciable deformation by the forces produced on firing the gun. Preferably the block is made of soft and light metal, such as Dur-al for example, and has a conical cavity 6 in its forward end, to receive and surround the tip 4 of the fuze but sufliciently large to be spaced from said tip at all points.

A seal is provided at 7 between the base 3 of the projectile 1 and the forward annular surface of the block 5. This seal may be sufliciently tight if both contacting surfaces fit closely. However, it is preferred to assure gastightness by using a Woodbridge seal and to provide a temporary adhesion by a coating at 7, such as Miracle Black Magic Adhesive, a product of Miracle Adhesives Corporation, New York, NY. In either case, the pressure of the combustion gases in the gun barrel will force the block 5 tightly toward the base 3 and assist in making the joint tight.

The Woodbridge seal depends upon differential pres sure inside and outside the protector. The total force pushing against the exposed rear face of the protector is resisted by the force in the opposite direction acting on the smaller area of the annular sealing face, which 0bviously will be much less, even though some of the gas pressure gains access to said sealing face. The explosion gases thus help to provide their own seal against access to the fuze.

In operation, when the shell 1 with protector 5 applied thereto is fired from a gun, it will spin in the conventional way, and the block 5 will participate in this spin. However, shells always have a little yaw and this yawing will set up shearing stress at the joint 7 which will loosen the block 5 from the base 3, and cause it to shift a little off center. Thereupon the centrifugal force due to spin will cause the now off-balance block to leave the shell. As this block has very poor ballistic characteristics, that is, it has the conical cavity 6 in its forward end instead of an ogive, it will not travel far, and. usually will drop to the ground after the shell has travelled a relatively short distance.

The protectors 5 are expendable, and need not be recovered after firing.

In the modified form of the invention, illustrated in Fig. 2, a much lighter and thinner protector is provided. In this view the projectile is shown at 10 and the base thereof at 11. The protector in Fig. 2 consists of a metal plate 12 having a frusto-conical central element 13 defining a cavity 14 therein to receive and protect the projecting tip 15 of a fuze '16 in the base 11. A Woodbridge seal is formed by an annular plane portion 17 of plate 12 in close contact with the flat end of the projectile. The plate 12 is formed with a rim 18 having a flange 19 between which and the projectile base there is positioned a helical spring 20. The spring 20 is in compression when the protector is in position, and thus tends to project said protector from the projectile base. In order to prevent such action from occurring prematurely, however, a temporary attachment of the protector to the tip 15 of the fuze is provided. This attachment consists of providing an extension 21 for the fuze tip 15 projecting said extension through a suitable opening in the apex of the tip, and cementing the projecting part of the extension to the outer surface of said apex with a cellulose plastic, as shown at 22. If desired, the extension may be soldered to the apex with a low melting point alloy, such as Woods metal, or by screw threads.

The modified protector shown in Fig. 2 possesses several advantages over the type shown in Fig. 1. It may be manufactured much more cheaply, as it can be made by punch-press techniques, and it occupies far less space in storage and shipment. Also, it requires much less material, while still aifording adequate protection to the fuze, particularly against injury by unburnt or partlyburnt particles of propellant that might otherwise adhere to or penetrate the fuze housing.

The protectors may be made of any suitable material having sufficient strength and toughness, such as steel, aluminum, Dural, copper, and many other metals and alloys.

The Fig. 2 form employs no adhesive in the joint between projectile and protector, and relies entirely on the Woodbridge seal. Moreover, the releasing and discarding of the protector of Fig. 2 does not depend on yaw and/or centrifugal force, but is provided by the positive action of the spring 20, which pushes off the protector as soon as said protector is released from the tip of the fuze, by the heat of the combustion gases or by the unscrewing of the screw of similar hand to the spin of the projectile.

As pointed out in the statement of objects of the invention, the improved protector will function to protect a proximity fuze from the efiects of any stray electric charges near the gun muzzle, to prevent premature detonation of the shell in which the fuze is mounted.

What is claimed is:

1. The combination with a projectile having a base,

and a fuze mounted in the base and having a portion projecting beyond the base, of a protector comprising a metal plate having a conical central element defining a cavity to receive the projecting fuze portion, a plane portion surrounding the central element and engaging the projectile base, a rim on the plane portion, a flange on the rim and extending radially therefrom, a spring surrounding the rim and held in compression between the flange and the base, and a releasable connection between the projecting fuze portion and the central element for normally retaining the protector in position on the projectile base, said spring urging the protector away from the base upon release of the releasable connection.

2. The combination of claim 1, wherein said releasable connection consists of an extension on the projecting fuze portion and projecting through the apex portion of the central element, and a fusible connector interconnecting the apex portion and the extension.

3. In a projectile having a base, and a fuze mounted in said base and having a portion projecting beyond said base, a protector for said projecting fuze portion, comprising, a central element enclosing said projecting fuze portion and engaging said base, a flange on said central element and extending radially and outwardly therefrom, resilient means held in compression between said flange and said base, and a releasable connection between said central element and said projecting fuze portion for normally retaining said protector in engagement with said base, said resilient means displacing said protector from engagement with said base upon release of said releasable connection.

References Cited in the file of this patent UNITED STATES PATENTS 45,462 Henry Dec. 13, 1864 405,690 Ball June 25, 1889 657,248 Phillips Sept. 4, 1900 1,459,198 Dunajeff June 19, 1923 2,055,765 Hayden Sept. 29, 1936 2,382,152 Jakobsson Aug. 14, 1945 2,386,054 McGee Oct. 2, 1945 FOREIGN PATENTS 865,025 France Feb. 10, 1941 

